The medical industry is constantly evolving through the adaptation of improved pharmaceutical, biotechnology, and medical device products and procedures. Techniques and technologies are being developed to treat internal areas of the body through less invasive means.
It is often desirable and frequently necessary to remove a portion of tissue from humans and other animals, particularly in the diagnosis and treatment of patients with cancerous tumors, pre-malignant conditions and other diseases or disorders. Typically, in the case of cancer, when the physician establishes by means of procedures such as palpation, x-ray or ultrasound imaging that suspicious circumstances exist, a biopsy is performed to determine whether the cells are cancerous. Biopsy may be done by an open or percutaneous technique. Open biopsy removes the entire mass (excisional biopsy) or a part of the mass (incisional biopsy). Percutaneous biopsy, on the other hand, is usually done with a needle-like instrument and may be either a fine needle aspiration (FNA) or a core biopsy. In FNA biopsy, individual cells or clusters of cells are obtained for cytologic examination and may be prepared such as in a Papanicolaou smear. In core biopsy, as the term suggests, a core or fragment of tissue is obtained for histologic examination which may be done via a frozen section or paraffin section. The type of biopsy utilized depends in large part on circumstances present with respect to the patient and no single procedure is ideal for all cases. However, core biopsy is extremely useful in a number of conditions and continues to be used frequently by the medical profession.
To arrive at a definitive tissue diagnosis, intact tissue is needed from an organ or lesion within the body. In most instances, only part of the organ or lesion need be sampled. However, the portions of tissue obtained must be representative of the organ or lesion as a whole. In the past, to obtain tissue from organs or lesions within the body, surgery had to be performed to locate, identify and remove the tissue. With the advent of medical imaging equipment (x-rays and fluoroscopy, computed tomography, ultrasound, nuclear medicine, and magnetic resonance imaging) it has become possible to identify small abnormalities even deep within the body. However, definitive tissue characterization still requires obtaining adequate tissue samples to characterize the histology of the organ or lesion. For example, mammography can identify non-palpable (not perceptible by touch) breast abnormalities earlier than they can be diagnosed by physical examination. Most non-palpable breast abnormalities are benign; some of them are malignant. When breast cancer is diagnosed before it becomes palpable, breast cancer mortality can be reduced. However, it is often difficult to determine if pre-palpable breast abnormalities are malignant, as some benign lesions have mammographic features which mimic malignant lesions and some malignant lesions have mammographic features which mimic benign lesions. Thus, mammography has its limitations. To reach a definitive diagnosis, tissue from within the breast must be removed and examined under a microscope. Early biopsy techniques for reaching a definitive tissue diagnosis for non-palpable breast disease required a mammographically guided localization, either with a wire device, visible dye, or carbon particles, followed by an open, surgical biopsy utilizing one of these guidance methods to lead the surgeon to the non-palpable lesion within the breast.
Open surgical breast biopsies have many drawbacks. They can be disfiguring, expensive and are imperfect. Open surgical biopsies also carry a small mortality risk (due to the risks of anesthesia) and a moderate morbidity rate (including bleeding, infection, and fracture or migration of the localizing wire). In cases where multiple lesions are present in the breast, a surgeon is reluctant to biopsy each lesion due to the large tissue mass that must be extracted with each lesion. The most convenient lesion may be taken which most often results in an incomplete diagnosis.
Percutaneous breast biopsy techniques are more desirable in many instances, particularly in light of modern imaging techniques which are able to pinpoint non-palpable tissue masses in the breast and consequently, the increased frequency of biopsies that are necessary for diagnosis of these tissue masses. A well known instrument used quite extensively for core biopsies in the past is manufactured by Travenol Laboratories of Deerfield, Ill., and is sold under the mark “TRU-CUT.” This manual biopsy instrument at one time enjoyed as much as 98% of the market for such devices. As disclosed in U.S. Pat. No. 3,477,423, the instrument comprises a two-piece assembly: an outer cutting cannula mounted to one hub member and an inner stylet with a sampling notch ground into it mounted to a second hub, with the hubs being slidably interlocked. The instrument is assembled and placed into the body with the outer cutting cannula just to the rear of a lancet point or beveled distal end of the stylet. Upon inserting the device up to or in front of the area to be biopsied, advancement of the assembly is halted. The stylet is manually advanced distally of the cannula with the cannula held stationery. Upon advancement of the stylet, the specimen notch is exposed. Tissue surrounding the stylet prolapses into the specimen notch and the cutting cannula is then manually advanced distally over the stylet, slowly shearing off the tissue entrapped in the stylet's specimen notch. The instrument is then either (a) withdrawn and the stylet advanced distally to expose the tissue for preparation for study or (b) left in place and only the stylet is proximally removed from within the cannula so a determination of successful sampling may be made. If the sampling was not successful, the stylet may be reinserted into the cannula, which remains positioned within the patient, and an attempt to reposition the assembly of stylet and cannula and repeat sampling can be made.
Such a technique using this basic design of a biopsy instrument is referred to as a manual technique. One drawback to the manual technique is that it requires a great deal of manual dexterity and motor coordination, along with the use of both hands, to advance the stylet while maintaining the position of the cannula and then to maintain the position of the stylet while advancing the cannula. Another drawback is that the cannula is advanced relatively slowly, resulting in an extremely poor cutting action and allowing the surrounding tissue an opportunity to collapse, thus making no use of the stored kinetic energy in the material being severed. Further disadvantages are encountered when the tissue volume to be sampled contains areas of higher density than that of surrounding tissue, such as areas of calcification commonly associated with certain types of cancerous growths. A manually inserted sampling device is often incapable of penetrating the denser area of tissue which merely deflects the course of the cannula/stylet structure around the dense area and into the more compliant surrounding tissue. In the late 1980's, two different stereotactic guidance systems were modified to allow the guiding portion of each system to accommodate spring powered devices such as the Biopty® (Bard Radiology) gun. As used herein, the term “gun” is used to refer to a tissue sampling device designed for “one-handed” operation. A feature common to many of these devices is the shape of the device being adapted to fit the hand of a medical practitioner with a pistol-like grip, complete with a triggering mechanism. Free-hand ultrasound guidance techniques were also developed to guide the Biopty® gun to breast lesions detected by ultrasound.
With image-guided percutaneous core breast biopsy, it should be possible to greatly reduce the number of open, surgical breast biopsies performed. However, there are limiting factors with image-guided breast biopsies. Conventional, manually operated two-step devices are awkward to manipulate, and the tissue samples obtained thereby are often unsatisfactory.
A variety of automatic and semiautomatic biopsy instruments have been developed which are spring loaded gun-type devices. A biopsy gun currently used is described in U.S. Pat. No. Re. 34,056, entitled “TISSUE SAMPLING DEVICE,” issued to Lindgren et al. Additional examples of biopsy gun devices are disclosed in U.S. Pat. Nos. 4,600,014 and 4,958,625.
Such devices use a design comprising a handle held in a physician's palm, and a guide tube extending forwardly of the handle. A cannula is slidably disposed within the guide tube and is movable from within the guide tube forwardly out of the distal end of the guide tube. A sampling stylet is telescopically disposed within the cannula and projects from the rear of the handle. In an automatic mode of operation, the cannula, when in the retracted position, is spring loaded by means of a compressed spring. A release lever, which works against the compressed spring, is activated to release compression of the spring which then expands and pushes the cannula outwardly over the stylet. This instrument, as stated, requires two handed operation. Also, since the stylet is not removable proximally from within the handle, the entire instrument must be withdrawn to obtain access to the sample.
A fully automatic instrument manufactured by Radiplast, Inc. of Sweden is described in U.S. Pat. No. 4,699,154. This instrument comprises a reusable, spring-loaded box-shaped housing or handpiece, which activates a disposable cannula and stylet set. Both the stylet and cannula are activated in rapid succession. The instrument has the advantage of reducing the dexterity and motor coordination necessary in the use of manual devices and also eliminates the slow cutting action of the manually advanced cannula, replacing it with a very quick, clean cut. This instrument, however, also has its drawbacks. First, the reusable handpiece is very large, heavy, cumbersome, and expensive. They are also typically spring-powered devices and must be manually cocked with some sort of plunger bar. Such “cocking” of the gun requires considerable force and the gun must be cocked for each biopsy cut. When actuated, the springs provided in the gun accelerate the needles until a mechanical stop position is reached which can create a loud snapping noise and jerking motion which is a problem both to the physician and the patient. A further drawback is encountered in automatically activating both the stylet and the cannula, as opposed to activating the stylet manually, in that the rapid speed at which the cannula follows the stylet into the tissue does not allow much tissue to collapse into the specimen notch, limiting the size of the sample.
U.S. Pat. No. 5,183,054, entitled “ACTUATED BIOPSY CUTTING NEEDLE WITH REMOVABLE STYLET,” issued to Burkholder et al., discloses a biopsy device having a tubular cannula through which a stylet, having a stylet cavity near the distal end, is placed. The stylet is removable from the cannula and removed from the biopsy device through the housing so that the tissue sample obtained by the biopsy device may be manually retrieved while the cannula remains in place within the patient, near the area being sampled. Thereafter, the stylet may be reinserted through the housing and cannula into the patient's tissue where additional tissue samples may be obtained. In this way, trauma to the tissue that ordinarily occurs upon reinsertion of the cannula and stylet is minimized.
U.S. Pat. No. 5,234,000, entitled “AUTOMATIC BIOPSY DEVICE HOUSING A PLURALITY OF STYLETS,” issued to Hakky et al. describes a biopsy device for taking a plurality of samples of tissue from a living being. The device comprises a housing having a portion arranged to be held by a person using the device, a cannula having a proximal portion and a distal portion and being coupled to the housing. A plurality of stylets are located in the housing, with each of the stylets having a proximal end, a distal end, and a tissue receiving notch located adjacent the distal end. Each stylet is individually propelled through the cannula into the body so that a portion of the tissue prolapses into the notch.
There currently exists a need for a more effective microsurgical device for obtaining a sample of breast tissue from a patient.